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Pets & COVID-19 in the literature

Nature article on increased susceptibility of cats to COVID-19

In a recent Chinese study, cats were found to be infected with COVID-19 more easily than dogs and cats appear able to spread it to other cats. It is unclear how they transmit it to each other. Dogs are less likely to transmit the virus. There is no strong evidence of cats spreading COVID-19 to humans.

Animal source of coronavirus

New research re-evaluates the possible source of COVID-19 as the pangolin. Although the spike proteins in pangolin coronavirus and SARS-CoV-2 are similar, the rest of the virus is less so, meaning that pangolins are not the likely intermediate host. Currently, the closest match to the human coronavirus is found in a bat from China’s Yunnan Providence. COVID-19 is thought to have originated from bats.

Spread of coronavirus to humans

New research (yet to be published) suggests that pangolins could be a possible source of COVID-19 infection transmitted to humans. Researchers at the South China Agricultural University compared coronaviruses from these animals with that of humans infected with (what was then called) nCoV-2019 and found that their genetic sequences were 99% the same.  Pangolins are scaly animals commonly used in traditional Chinese medicine to treat arthritis, menstrual problems, and other illnesses. Pangolins are protected animals and sale is punishable by 10 years or more of prison. However, they are sold illegally for their meat and scales. Previous research in Guangzhou identified coronavirus as a common pathogen found in dead pangolins.

A comparison of 2019-nCoV to SARS-CoV to identify possible animal transmission

A structural analysis of previous SARS-CoV and ACE2 receptor interactions showed many similarities with (what was then called) 2019-nCoV. These interactions are important in cross-species and human-to-human transmission. Phylogenetic analysis shows that residue 493 in 2019-nCoV RBD, the receptor binding domain of the spike protein (similar to residue 479 in SARS-CoV) is likely what allowed for animal-to-human transmission and residue 501 in 2019-nVoV RBD (similar to residue 487 in SARS-CoV) likely enabled human-to-human transmission. This article suggests that the 2019-nCoV receptor recognizes the ACE2 receptors of pigs, ferrets, cats, orangutans, monkeys, bats, and humans. 

Cats testing positive for COVID-19

This is a non-peer reviewed article that evaluated serum from 102 cats in Wuhan, China. They found that 15 of the 102 cats were positive for the receptor binding domain (RBD) of SARS-CoV-2 by indirect enzyme linked immunosorbent assay (ELISA).

Domestic animals and coronavirus susceptibility

This non-peer reviewed article looked at the transmission and sites of  SARS-CoV-2 replication in ferrets, cats, dogs, ducks, pigs, and chickens.  In all 6 species they evaluated possible infection with direct inoculation and exposure. During this experiment, they evaluated nasopharyngeal swabs, rectal swabs, and organs after euthanasia. They found that cats and ferrets were more likely to sero-convert than dogs. They also found feces of cats to be positive for SARS-CoV-2. Ducks, pigs, and chickens were not susceptible to the virus.